Method and device for keeping clean ends of spray damping mechanism nozzles on rotary printing press

ABSTRACT

Deposits are removed from the end of a spray dampening nozzle which is used to spray pressurized fluid that is delivered to the nozzle end. This fluid is activated by ultrasound before it exits the nozzle end. The activation of the fluid can be accomplished upstream of, or at the nozzle end. An ultrasound vibrator is used to activate the fluid and is either directly or indirectly connected to the fluid by a vibration transmitter.

FIELD OF THE INVENTION

The present invention relates to a method keeping clean a nozzlemouthpiece of a nozzle of a spray moistening device of a rotary printingpress; the and to a device for executing the method.

DESCRIPTION OF THE PRIOR ART

A spray moistening device with spray nozzles, which are arranged next toeach other in the axial direction on a so-called spray beam formoistening a printing cylinder of an offset rotary printing press, isknown from U.S. Pat. No. 4,044,647.

U.S. Pat. No. 4,241,656 discloses a self-cleaning nozzle of a spraymoistening device for a rotary printing press. Here, a moistening agentis swirled with air after exiting from a nozzle mouthpiece.

EP 0 126 536 A2 describes a pushbutton for a ink jet printer. The inkreservoir, the nozzle plate and nozzle bores arranged therein arecleaned by means of ultrasound excitation. The ultrasound excitation isactivated during the cleaning operation.

DE 31 08 541 A1 discloses a device for generating a moistening agent fogfor a moistening device of an offset printing press, using an ultrasoundatomizer.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide a method forkeeping the nozzle mouthpieces of a spray moistening device clean, aswell as an associated device, by means of which it is possible toperform preventive maintenance on spray nozzles of a spray moisteningdevice without having to remove them.

This object is attained in accordance with the present invention byperiodically activating the moistening agent that is supplied to thenozzle mouthpieces of the spray moistening device by the use ofultrasound upstream of, or in the nozzle mouthpieces. An ultrasoundvibration transmitter is in communication with the fluid either in anupstream fluid chamber, or at the nozzle mouthpiece;

The advantages which can be achieved by means of the present inventionlie, in particular, in that the fluid conducted through the nozzles canbe activated by means of ultrasound because of the arrangement of amoistening agent, which in the operational state, is not activated byultrasound during a spraying process and is charged with pressure, orrespectively by an ultrasound vibration transmitter, which can beswitched on during a cleaning process. When the fluid activated byultrasound exits through the nozzles, the paper and ink particles on thenozzle outlet opening, or respectively on the nozzle mouthpiece, areremoved.

In this way, it is easily possible to perform preventive cleaning of thespray nozzles without having to remove the nozzles. A long, trouble-freeoperation of the moistening device is made possible by the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is represented in the drawings by two preferredembodiments and will be described in more detail in what follows. Shownare in:

FIG. 1, a cross section through the schematic representation of a spraynozzle unit with a device; in accordance with a first preferredembodiments of the present invention; and

FIG. 2, a detailed representation of a spray nozzle with a device in asecond preferred embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A nozzle unit 1 of a spray moistening device for moistening objects,such as, in particular a rotatable moistening distribution roller,consists of a nozzle housing 2, which is fastened by means of fasteningelements, for example screws, on a first sheet metal plate 4 of avibration-damping plate generally at 6. The vibration-damping plate 6 isarranged by means of screws on a crosspiece 9 of a nozzle beam.crosspiece 9 receives a plurality of nozzle units 1 arranged at adistance next to each other.

The nozzle housing 2 has a chamber 11, which extends in the interior ofnozzle housing 2 in the horizontal direction, for example, and which isbordered on one side by a nozzle mouthpiece 13, held in place by a unionnut 12, and a nozzle 14 fastened thereon. On its side opposite thenozzle mouthpiece 13, the chamber 11 is bordered by a coil holder 16,that is screwed to the nozzle housing 2, and which supports or holds amagnetic coil 17. A valve rocker 19 is arranged in the interior of themagnetic coil 17 valve rocker 19 has, at its end facing the nozzlemouthpiece 13, a sealing element 21 for closing an outlet bore 22located in the nozzle mouthpiece 13. The magnetic coil 17 is providedwith a connecting cable 20. During the operation of the magnetic coil17, the valve rocker 19 can be moved back and forth in the horizontaldirection A, so that the bore 22 located in the nozzle mouthpiece 13will be opened and closed by means of the sealing element 21. The valverocker 19 is sealed against the chamber 11 at the end of the magneticcoil 17 by means of a sealing ring 10.

The nozzle housing 2 has a supply bore 24, for example on its upperside, which is connected with the chamber 11 and, via a valve 26, with apressurized water inlet 27. Opposite the bore 24 for the water inlet 27,the nozzle housing 2 is provided with a fastening connector 28, which isalso connected with the chamber 11. The fastening connector 28 receives,in its axial direction, a profiled, pipe-shaped intermediate piece 29,which is made of a vibration-damping material and on whose end isfastened a known ultrasound vibration generator 31. The ultrasoundvibration generator 31 is provided with a cable 30 extending to acontrols means 35. A sealing ring 25 is arranged between theintermediate piece 29 and the nozzle housing 2.

The ultrasound vibration generator 31 can be embodied as apiezo-mechanical ultrasound vibration generator with a generatedfrequency between 20 and 30 kHz, which has a plurality, for examplefour, ceramic rings 33 arranged one behind the other on a rod-shapedvibration transmitter 32. An interior end 34 of the rod-shaped vibrationtransmitter 32, which points in the direction toward the chamber 11 andprotrudes out of the ultrasound vibration generator 31, extends at leastas far as into the chamber 11, as seen in FIG. 1.

The following procedure is followed in the course of cleaning the nozzleinsert 14, or respectively the nozzle mouthpiece 13: the sealing element21, which is located on the valve rocker 19, is fixed in place at adistance from the outlet bore 22 of the nozzle mouthpiece 13 in such away that when the valve 26 is open a pressurized fluid 39, for examplewater, can exit through the chamber 11, the outlet bore 22 as well asthe bore in the nozzle insert 14 at a spraying pressure of 3.5 bar, forexample. The water inside the chamber 11 is activated by ultrasound byswitching on the ultrasound vibration generator 31 through the controlmeans 35. In the process, the water is alternatingly placed in atraction phase and an overpressure phase by means of the vibrationtransmitter 32 protruding into the chamber 11 with itsvibration-transmitting end 34. When the water exits the nozzle insert14, the shock waves being generated in the water destroy theaccumulations of dirt, typically consisting of paper and ink particles,located on the nozzle mouthpiece 13 or on the nozzle insert 14.

The vibration-damping components 29, 6 are arranged to protect thenozzle housing 2 as well as the crosspiece 9 supporting the nozzle unit1 from direct ultrasonic effects.

In accordance with a variant of the above described embodiment, thevibration as seen in FIG. 1, transmitting end 34 of the vibrationtransmitter 32 is connected with the beginning or first or inner end ofa vibration-transmitting cup 37 that is arranged coaxially with thevalve rocker 19. An outer or second end 40 of the vibration-transmittingcup 37 extends as far as the nozzle mouthpiece 13 and is provided therewith a centered bore 38. Because of this arrangement, during thecleaning process, the fluid 39 supplied through the valve 26 and locatedin the chamber 11 can pass through the outlet bore 22 as well as thenozzle insert 14 when the sealing element 21 of the valve rocker 19 hasbeen retracted.

Because of the additional inclusion of the vibration-transmitting cup37, it is possible to transmit the ultrasound directly as far as thevicinity of the nozzle mouthpiece 13 and therefore into the vicinity ofthe nozzle insert 14. Inside the chamber 11, the fluid 39 is thus indirect connection with the vibration transmitter which includes thetransmitter 31, rod 32 and cup 37.

In accordance with a second preferred embodiment of the presentinvention, an ultrasound vibration generator 41 is arranged, fixed inplace on the crosspiece 9, by means of a vibration-damping holder 42,and above a nozzle mouthpiece 13 receiving a nozzle insert 14, all asseen in FIG. 2. A rod-shaped vibration transmitter 43 connects a numberof ceramic rings 33. This vibration transmitter 43 is fixedly connected,with its vibration-transmitting end 44, which is located outside of theultrasound vibration generator 41, with a ring-shaped holder 46 that isfixedly arranged around the nozzle mouthpiece 13, or which is connecteddirectly with the nozzle mouthpiece 13. In this case, the nozzlemouthpiece 13 can be provided with a coating 23, which is insensitive toultrasound vibrations, on its circumference as well as on its sidefacing away from the nozzle insert 14, again as shown in FIG. 2.

The fluid 39 exiting from the nozzle insert 14 is in indirect contact,-via the nozzle insert 14, the nozzle mouthpiece 13, and the vibrationtransmitter 43 with the ultrasound vibration generator 41.

It is also possible to clean a nozzle insert 14 during the clocked ortimed output of the moistening agent through the nozzle insert 14, i.e.during the opening of the electromagnetically actuated valve rocker 19,or respectively of the sealing element 21. The flowthrough amount ofmoistening agent through the nozzle insert 14 is a function of the pressspeed. With a continuous valve opening time, for example of 15 ms, aclock period length, for example of 250 ms, can be changed. By means ofthe permanent switching on of the ultrasound vibration generator 31 or41 over a defined period of time, for example 30 s, the moistening agentexiting the nozzle insert 14 is activated several times by ultrasoundand thus will have destroyed the paper and ink particles located at thenozzle insert 14.

The same result can be achieved if the moistening agent is in indirectcontact with the ultrasound transmitter 32 or 43.

While preferred embodiments of a method and device for keeping cleanends of spray damping mechanism nozzles on a rotary printing press inaccordance with the present invention have been set forth fully andcompletely hereinabout, it will be apparent to one of skill in the artthat a number of changes in, for example, the types of printing pressused, the specific type of printing being done, the fluid supply systemand the like may be made without departing from the true spirit andscope of the present invention which is accordingly to be limited onlyby the following claims.

What is claimed is:
 1. A method for keeping a nozzle mouthpiece of anozzle of a spraying device for a spray moistening device of a rotaryprinting press clean including:providing a moistening fluid; providing aspray moistening device;providing a nozzle unit in said spray moisteningdevice, said nozzle unit having a moistening fluid receiving chamber anda nozzle mouthpiece; selectively operating said spray moistening devicein one of an operational state and a cleaning process; supplying saidmoistening fluid under pressure to said nozzle mouthpiece through saidmoistening fluid receiving chamber while said spray moistening device isoperating in both said operational state and said cleaning process;providing an ultrasound vibration generator; providing an ultrasoundvibration transmitter extending between said ultrasound vibrationgenerator and said nozzle unit; operating said ultrasound vibrationgenerator; using said ultrasound vibration transmitter forultrasonically activating said moistening fluid supplied to said nozzlemouthpiece only when said spray moistening device is operating in saidcleaning process; and using said ultrasonically activated moisteningfluid for cleaning said nozzle mouthpiece only when said spraymoistening device is operating in said cleaning process.
 2. A device forkeeping a nozzle mouthpiece of a nozzle of a spraying device for a spraymoistening device of a rotary printing press clean comprising:a spraymoistening device operable in both an operational state and a cleaningprocess, said spray moistening device including a nozzle unit; a nozzlehousing in said nozzle unit, said nozzle housing including a moisteningfluid receiving chamber; means to supply a moistening fluid to saidmoistening fluid receiving chamber; a nozzle mouthpiece secured in saidnozzle housing in fluid communication with said fluid receiving chamberand receiving said moistening fluid; a periodically operable ultrasoundvibration generator; and an ultrasound vibration transmitter extendingbetween said ultrasound vibration generator and said nozzle unit andultrasonically activating said moistening fluid in said nozzlemouthpiece, said ultrasound vibration generator including control meansfor operating said ultrasound vibration generator to ultrasonicallyactivate said moistening fluid through said ultrasound vibrationtransmitter only when said spray moistening device is operating in saidcleaning process.